This invention relates to a system and a method for harvesting a generally cylindrical tissue structure from the body of a patient. More particularly, the invention is directed to a system and a method for harvesting a section of a blood vessel from a patient.
In certain circumstances it is desirable to remove sections of tubular tissue structure from a patient""s body. Such tissue may be used in another part of the patient""s body, may be transplanted into a second patient""s body or may be discarded. As used herein, the term xe2x80x9ctubular tissue structurexe2x80x9d includes blood vessels, tendons, bile ducts, nerves and any other similar tissue formation which is generally tubular in structure and capable of being separated from surrounding tissue. Although the invention herein will be discussed in terms of harvesting blood vessels it should be understood that the apparatus and method described are equally applicable to harvesting other solid or cylindrical tubular tissue structure.
Vein harvesting is commonly done in connection with coronary artery bypass surgery. The saphenous vein is a subcutaneous vein which is often used for coronary artery bypass grafting, infra-inguinal bypass grafting and vein-vein bypass grafting. Other vessels may also be used including the internal mammary artery, the radial artery, and/or the lesser saphenous vein. Previously, it has been necessary to make an incision along the full length of the vein section to be removed. The vein is then freed by severing and ligating the branches of the vein, after which the section of the vein can be removed from the patient. The full-length incision must then be closed, for example by suturing or stapling. Obviously, the harvesting of the vein in this manner leaves disfiguring scars which are cosmetically undesirable. Additionally, the large incision creates a risk of infection to the patient and may not heal properly, especially with those patients who have poor circulation in their extremities. Such an incision may create a chronic non-healing wound, requiring significant and costly medical treatment.
Devices for harvesting a section of a blood vessel without creating a full-length incision have been suggested and include that described in U.S. Pat. No. 4,793,346 (Mindich) and UK Patent No. GB 20 82 459A. These patents describe methods that use incisions at either end of the blood vessel to be harvested. Such devices and methods can be disadvantageous because greater blood loss than is necessary can result. These devices may also remove more tissue than is necessary because the size of the cutting device is not readily adaptable to the changes in the size of the blood vessel. In addition, these patents describe techniques which have a high probability of damaging the vessel, making it unsuitable for use as a vascular conduit.
In U.S. Patent No. RE 36,043 (Knighton), a device and a method for vein removal are disclosed which solve some of the problems associated with the use of prior art devices. Knighton discloses an endoscope having a lumen extending longitudinally through the scope body. The endoscope includes means for viewing an area adjacent the distal end of the lumen. The lumen has a lateral dimension large enough to accommodate the blood vessel being harvested and at least one tool for use in harvesting the blood vessel. A first end of the blood vessel section to be harvested is exposed through an incision in the patient""s body. A dissecting tool and a gripping tool are inserted through the lumen of the endoscope and used to dissect the blood vessel away from the surrounding connective tissue of the patient""s body. Additional tools are provided for use through the lumen of the endoscope to remove body fluids and coagulate bleeding tissue, to ligate and sever side branches from the blood vessel to be harvested, and to ligate and sever a distal end of the blood vessel to be harvested when a desired length of blood vessel has been dissected. Only a small incision in the patient""s body is necessary to harvest a relatively long length of blood vessel in a precise and controlled manner using this device and procedure.
U.S. Pat. No. 5,772,576 (Knighton et al.) also describes a device and method for vein removal. The device has one or more lumens extending through a body portion. One lumen is sized to accommodate a blood vessel and at least one tool for use in removing the vessel. The device may also include viewing means so that the operator may remotely view an area adjacent the distal end of the body portion. The device protects the vessel being removed from damage by the tools used in the procedure, which is critical since the blood vessel is destined for reuse (as in arterial bypass). In addition, a single operator can use the device.
In commonly assigned, co-pending application Ser. No. 09/715,665, (Knighton et al.) filed Nov. 17, 2000, entitled xe2x80x9cVein Harvesting System and Methodxe2x80x9d, the entirety of which is incorporated herein by reference, a system that is easier to use and minimizes damage to a blood vessel is described. In this system, a multi-lumen tube is used in conjunction with a housing having a removable lower portion. The housing provides a workspace for the removal of a blood vessel and the multi-lumen tube and associated tools provide a means to see and to remove a desired length of vein and cut and cauterize any vein side branches while minimizing damage to the vein and trauma to the patient. An additional problem with present technology is determining the course of the main saphenous trunk versus a large side branch. The course of the main vein would also be beneficial to see well ahead of the dissection to facilitate the speed of dissection.
The need also exists for a vein harvester having a variable length and further having tools that would be easier and more convenient to use. The tools typically used in the current procedures tend to be long and difficult to control. Having tools with a variable length would allow for an easier, more precise, and more rapid procedure.
This invention is a system and a method for the harvesting of a blood vessel. The system comprises an expandable hood to make a workspace for extraction of the vein and an extendible or telescoping device having desired tools at its distal end. The tools are activated at the proximal end of the telescoping device. The method comprises illuminating the dissection area via a light catheter that is inside the lumen of the blood vessel and deploying the telescoping device to the length desired to dissect the vein from surrounding tissue.
In a first aspect the invention is a method of harvesting a section of a vessel from a human or animal body. The method comprises exposing the vessel section to be harvested through an incision in the body; providing a light source; placing the light source in the lumen of the vessel, the light source being sufficient to illuminate substantially the entire vessel section and vessel side branches extending from the vessel section with an intensity which is visible from an exterior of the vessel section; dissecting the vessel away from surrounding connective tissue of the body with a dissecting tool inserted through the incision; viewing the dissection of the vessel with a viewing element inserted through the incision; cutting the vessel at proximal and distal ends of the vessel section; and removing the vessel section from the patient""s body. The vessel section may be exposed through first and second incisions with the dissecting tool and viewing element inserted through the first incision and the light source placed in the vessel lumen through the second incision. The first incision may be made over a proximal end of the vessel section and the second incision over a distal end of the vessel section. The method may further comprise providing a telescoping member having first and second substantially cylindrical segments, the second segment sized to fit within a lumen of the first segment, the telescoping member being adjustable in length from a fully collapsed position where the second segment is contained substantially within the first segment to a fully extended position where the second segment is substantially removed from the first segment, the telescoping member having the dissecting tool connected to a distal end of the second segment, and inserting the telescoping member through the incision. The step of proving the telescoping member may comprise providing a telescoping member wherein the viewing element and tool used to cut the vessel are connected to the distal end of the second segment. The method may comprise providing a hood member configured to be moveable from a first closed position to a second open position; inserting the hood member through the incision, adjacent the vessel; and creating a working space adjacent the vessel by opening the hood member from the first closed position to the second open position.
In another aspect the invention is a system for harvesting a section of a vessel from an incision in a human or animal body. The system comprises a light source sized and configured to be inserted into a lumen of the vessel, the light source being sufficient to illuminate substantially the entire vessel section with an intensity which is visible from an exterior of the vessel section; a viewing element configured to be insertable through the incision and capable of viewing the illuminated vessel section; and at least on tool used to harvest the vessel section, the at least one tool being sized to be inserted through the incision. This system may include a telescoping member having first and second substantially cylindrical segments, the second segment sized to fit within a lumen of the first segment, the telescoping member being adjustable in length from a fully collapsed position to a fully extended position by slidably adjusting the extent to which the second segment is contained in the lumen of the first segment, the telescoping element having a dissecting tool connected thereto. The viewing element may be connected to the telescoping member. A dissection element connected to the telescoping member may also be included. A hood member configured to be moveable from a first closed position to a second open position may be included in the system. The hood member is sized to be inserted through the incision in the closed position and placed adjacent the vessel section. The hood is further configured to create a working space adjacent the vessel when moved to the open position.